In recent years, a semiconductor device that processes an ultra-high frequency signal of a millimeter-wave and the like may been put in practical use. In such a case, the wavelength of a signal (radio frequency (RF) signal) becomes short as the operating frequency of the signal becomes high.
Apart from that, in a semiconductor device (semiconductor integrated circuit or LSI chip) on which a high frequency circuit such as an amplifier is mounted, e.g., when a chip (semiconductor substrate) is thicker than one-fourth (¼) of a signal wavelength that is used, a resonant mode occurs between the rear face of the chip and the circuit pattern of a front face.
In other words, in the case of an amplifying circuit, it is known that an output signal is fed back to an input terminal due to a resonance, which causes a problem such as an oscillation. Even if an oscillation does not occur, there may arise a problem, e.g., that a band characteristic deteriorates at a resonant frequency.
As mentioned above, e.g., in the semiconductor device including the amplifying circuit, the output signal is fed back to the input terminal due to the resonance, which causes the oscillation or the deterioration of the band characteristic or the like.
For that reason, e.g., it may be considered that a multilayer wiring structure is used, in which a ground plane (GND shield) is arranged in a lower layer so that a substrate is shielded from a signal electrode (pad electrode) in order to establish a structure that prevents an RF signal from leaking to the substrate.
However, when the GND shield is arranged in the lower layer of the pad electrode, e.g., the deterioration of a high frequency characteristic will be caused by a capacitance between the pad electrode and the GND shield.
Now, in a related semiconductor device that uses a high frequency signal, an idea may been proposed in order to reduce high frequency loss in a pad electrode and the like.
Patent Document 1: Japanese Laid-open Patent Publication No. 2003-224189